Instruct users to install minitest in the hamming docs
Instruct users to install minitest in the hamming docs

Specifically in the GETTING_STARTED.md document it says to expect
certain errors, but they'll see different errors if they're missing
Minitest. If you need the getting started guide in the first place,
then seeing the wrong errors is going to be very confusing.

gchan/xruby,jdsayle/xruby,NeimadTL/ruby,NobbZ/xruby,Insti/exercism-ruby,alexbrinkman/xruby,kickinbahk/xruby,kickinbahk/xruby,Insti/exercism-ruby,samilokan/xruby,kotp/xruby,Insti/xruby,samilokan/xruby,NeimadTL/ruby,Insti/xruby,Calvyn82/xruby,mamenama/xruby,rashmiagar/exercism,alexbrinkman/xruby,tommyschaefer/xruby,dalexj/xruby,NeimadTL/ruby,rashmiagar/exercism,kotp/xruby,remcopeereboom/xruby,exercism/xruby,tommyschaefer/xruby,exercism/xruby,Insti/exercism-ruby,dalexj/xruby,mamenama/xruby,jdsayle/xruby,wobh/xruby,NobbZ/xruby,darrencauthon/xruby,wobh/xruby,Calvyn82/word_count,Calvyn82/word_count,gchan/xruby,darrencauthon/xruby,Calvyn82/xruby,remcopeereboom/xruby